The present invention relates to wooden joist structures and metal connectors for interconnecting the wooden beams for forming such joist structures for enabling such wooden structures to be used to support structural loads.
In constructing wooden truss assemblies, in particular wooden joist structures, it has been common to use large wooden structural members, e.g. wooden members having a width of at least 10 inches. Such large wooden members, however, are becoming increasingly difficult to find and as a result have tremendously increased in cost. Consequently, various alternatives have been sought for enabling the construction of such truss structures utilizing more commonly available wooden beams such as 2 inch by four inch wooden beams. In seeking to find such alternatives, there have been two primary criteria that had to be met. First, the alternative device had to be able to withstand large compressive loads so that the trusses that were constructed could be used for bearing substantial structural loads. Secondly, it was considered desirable to develop alternative devices that could be prefabricated at a manufacturing plant and then easily shipped to a building site without a high degree of risk of incurring damage to the wooden structure.
Several types of devices have been developed for prefabricating truss structures such as illustrated in the following United States patents: U.S. Pat. No. 3,025,577 to Jureit; No. 3,298,151 to Jureit; No. 3,503,173 to Jureit; No. 4,078,352 to Knowles; No. 4,207,719 to Knowles; and No. 4,348,850 to Reeder et al. Each of these patents illustrates a metal web member stamped out from a piece of sheet metal with the web member having at least one leg with connector plates located at both of the extremities of such leg.
The patents to Jureit all disclose metal web members having a single leg with connector plates located at both of the extremities of such leg. Each of the connector plates has a plurality of teeth that are stamped out from the plate, which teeth then are embedded in the wooden members that are to be interconnected by the web member. The last of these three noted patents to Jureit discloses the use in the web members of several locating tabs to assist in arranging the web members on the wooden beams.
The patents to Knowles as well as the patent to Reeder et al. disclose V-shaped metal web members having connector plates both at their apex and at the extremities of the two legs of the V-shaped member. In the web members disclosed in the patents to Knowles, each of the legs of the web members has extending along substantially its entire length a rib that extends outwardly from the leg and side flanges extending in the opposite direction as the rib. Each of the connector plates in the metal web members disclosed in the patents to Knowles has a plurality of teeth that are struck out from the plate with these teeth extending in a direction opposite the direction in which the rib along each leg extends. In the web member disclosed in the patent to Reeder et al., each of the end plates also has a plurality of teeth struck out from such plate and several locating tabs are provided to assist in arranging the web members on the wooden beams. The web members disclosed by these patents are used in prefabricating truss assemblies at a manufacturing plant with such assemblies then being shipped to a building site.
An improved V-shaped metal web member is disclosed in commonly assigned U.S. application Ser. No. 337,691 entitled "Truss Structures Constructed With Metal Web Members" and filed Jan. 7, 1982. The V-shaped metal web members shown in such patent application are used for interconnecting elongated wooden members for forming a truss or joint assembly. The two elongated wooden members are arranged so as to extend parallel to each other with the web members interconnecting the two elongated members. Each of the metal web members is placed in the spacing between the wooden members and have their extremities connected to the wooden members. A plurality of pairs of teeth are stricken from each of the connector plates located both at the apex of the web member and at each of its extremities. Each of the legs of the web member has at least one groove which extends from the same side of the metal web member as the teeth. Each of the legs also has side flanges that extend on both sides of the leg for the entire length of the leg which flanges extend in the same direction as the groove.
The teeth which are struck out from the connector plates in the metal web member illustrated in the above-noted commonly assigned patent application are the same as those used in the structural joint connector disclosed in commonly assigned U.S. Pat. No. 4,343,580. The same types of teeth as disclosed in this commonly assigned patent are used in the preferred embodiment of the ribbed connector of the present invention. The subject matter of U.S. Pat. No. 4,343,580, therefore, is hereby incorporated by reference. As disclosed in such patent, the connector plate has a plurality of pairs of teeth punched out from the plate. Each of the pairs of teeth is struck from the plate so as to leave a corresponding longitudinally extending slot between the teeth. Each of the teeth has a knife edge portion which extends from the plate. This knife edge portion is thinner than the remaining portion of each tooth and has a sharp edge with a cross-sectional angle of less than 20.degree. and preferably between 8.degree. and 12.degree.. This knife edge portion facilitates penetration of each of the teeth into the wooden members to be secured together.
In constructing the wooden joist members with the metal web connectors, the length of the joist structures is limited since such length is primarily dependent upon the fixed length of the V-shaped web members although such length can be slightly varied by the use of half web members in the vicinity of the ends of the joist structures. In addition, the compressive loads applied to such joist structures formed with the use of such V-shaped web members is transferred into transverse forces along the joist structure since the legs of the web member extend at non-perpendicular angles between the wooden beams.